It has previously been proposed to control hand tools, appliances and the like, in accordance with various desired operating functions. Basically, a main ON-OFF switch is provided and additional control functions are usually obtained by associating with the basic switch a further control housing which is connected to the switch by a screw connection, welding, or the like. It is also known to incorporate continuous speed control with an ON-OFF switch. It has also been proposed to connect RF suppression capacitors to such switches, for example by means of a spring biassed clip. The capacitor is usually separately secured in the housing of the tool or appliance. Various additional control elements may be associated with the tool or appliance, and located at positions which are convenient for placement of the element although they may not necessarily be convenient for the user. Frequently such additional elements are located at positions other than the ON-OFF main switch itself.
If a single type of motor for a specific type of tool is to be offered to the trade with various types of operating function controls, then it is necessary to provide a multiplicity of switches or switch combinations for the respective tool models of any one series, depending on the desired control function. This increases manufacturing costs and particularly increases storage and procurements costs as well as storage of replacement parts at service stations. The housing of the tool itself may have to be different for different types or models of the same basic series of machine tools in order to accommodate such additional elements which, further, increases the cost of production and hence of the final unit.
It is an object of the present invention to provide a modular switch and control unit construction in which the switch housing and the respective operating control units are so arranged that various desired operating functions can be associated with the respective switch units, or not, as desired for a specific model, without requiring changes in the basic modules being used. Various operating functions can thus be accommodated with a minimum of storage requirement for parts.